Recent Advances in Wireless Indoor Localization Techniques and System

Table 1

Comparisons of indoor position methods.

Method	Measurement type	Indoor accuracy	Coverage	Line of sight (LOS)/nonline-of sight (NLOS)	Affected by multipath	Cost	Notes
Proximity	Signal type	Low to high	Good	Both	No	Low	(1) Accuracy can be improved by using additional antenna. However, it will increase the cost.; (2) Accuracy is on the order of the size of the cells
Direction (AoA)	Angle of arrival	Medium	Good (Multipath issues)	LOS	Yes	High	(1) Accuracy depends on the antenna’s angular properties; (2) Location of antenna must be specified.
Time (ToA, TDoA)	Time difference of arrival	High	Good (Multipath issues)	LOS	Yes	High	(1) Time synchronization needs.; (2) Location of antenna must be specified
Fingerprinting	Received signal strength	High	Good	Both	No	Medium	(1) Need heavy calibration.; (2) Location of antenna is not necessary
Dead; reckoning	Acceleration, velocity	Low to medium	Good	NLOS	Yes	Low	Inaccuracy of the process is cumulative, so the deviation in the position fix grows with time.
Map matching	An algorithm based on algorithms based on; projection and pattern; recognition	Medium	Medium (indoor); Good (outdoor)	NLOS	Yes	Medium	(1) Map matching purely focus on algorithms and not fully on position methods, coordinate transformation, and geocoding; (2) Using pattern recognition, high computing complex and poor real time issue occur.